The present invention relates to the field of testing working memory. More specifically the present invention relates to the field of testing working memory of visual inputs for predicting performance of air traffic control candidates.
The use of color on information displays has increased dramatically during the past decade. Many information displays require an operator to retain and recall displayed information. Working memory includes items remembered for a long time, newly perceived information, and an understanding of the perceived environment.
Compared to other coding schemes, color is an effective coding dimension to reduce search time in search and identification tasks [Cahill, M. C. and R. C. Carter. 1976. "Color Code Size for Searching Displays of Different Density," Human Factors, vol. 18, pp. 542-570; Christ, R. E. 1975. "Review and Analysis of Color Coding Research for Visual Displays." Human Factors, vol. 17, no. 6, pp. 542-570; Man Factors, Inc. 1980. Color Coding In Combat Direction System Displays. San Diego, Calif.]. Color coding is helpful when a display is unformatted, symbol density is high, the operator's task is complex, and color is logically related to the operator's task [Meister, D. 1984. Human Engineering Data Base For Design And Selection of Cathode-Ray Tube And Other Display Systems. Navel Personnel and Research Development Center. San Diego, Calif.]. Color is also useful for grouping related information, relocating already identified information, and assisting the operator in keeping track of critical information [Neil, D. C. 1980. Application of Color Coding In Tactical Display S-3A. (DTIC AD-A086-517) Navel Postgraduate School, Monterey, Calif.]. Color does not aid the operator when a task is easy or the display is uncluttered [Krebs, M. J., J. D. Wolf, and J. H. Sandvig. 1978. Color Display Design Guide. ONR Rept. N00014-77-C-0349, Honeywell, Inc. Arlington, Va.].
Rehmann's report on the use of color displays and air traffic control specifically mentions two studies that were performed by the Euro Control Experimental Center (EEC) [Rehmann, J. T. 1984. The Use of Color in Flight Service and Air Traffic Control. Federal Aviation Administration]. The EEC found that color improved aircraft identification and label overlap conditions and helped controllers in judging which velocity vector applied to which track. In addition, color simplified and speeded up the information sorting process.
Two stimulus dimensions are used as coding variables in many displays. Saenz and Richie studied the effect of color and location tasks and found that performance with color as a primary code did not significantly differ from performance with color as a redundant code (color and shape) [Saenz, N. E. and C. V. Riche. 1974. "Shape and Color as Dimensions of a Visual Redundant Code," Human Factors, vol. 16, no. 3, pp. 308-313]. Other studies indicate that redundant coding facilitates the location of targets as opposed to coding on a single dimension [Krebs, Wolf and Sandvig, supra]. Ludder and Barber found that color as a redundant code decreased time and improved flying performance on airborne CRT displays [Luder, C. B. and P. J. Barber. 1984 "Redundant Color Coding on Airborne CRT Displays," Human Factors, vol. 26, no. 1, pp. 19-32]. Another study recommended the use of redundant color coding to retain essential information in cases where color failure or color shifts are a function of display aging [Silverstein, L. D. and R. M. Merrifield. 1981. "Color Selection and Verification Testing for Airborne Color CRT Displays," Aircrew Display Symposium Proceedings]. Shape as the primary encoding scheme would endure if colors faded on CRT displays.
A monochromatic Naval tactical data system (NTDS) display was used in a figurative (green/red) display to study the effect of color on memory [Bruck, L. A. and P. W. Hill. 1982. Tactical Situation Displays and Figurative Symbology, Naval Postgraduate School, Monterey, Calif.]. The figurative symbology consisted of more life like images than the standard tactical symbology. Subjects viewed the display for 50 seconds. A map of the display then was provided for each subject. Subjects were required to recall the allegiance and type of symbols that were displayed at the marked locations on the map. There were no significant differences in accuracy between the two display conditions. In the color figurative display, the shape denoted the symbol type and color denoted allegiance.
Color was used as a coding dimension to decrease the necessity for mental recall in an antisubmarine warfare (ASW) tactical display using static formats [Oda, D. J. and B. W. Barker. 1979. "The Application of Color to ASW TActical Displays," Proceedings of the Society for Information Display, vol, 20/1]. The standard non-color coded ASW display formats with standard numerics and graphics in the normal green color were compared with ASW formats of the same type but with color coding added to signify the age of the display data. Each static display represented a point in time for an ASW airborne localization mission. The subjects determined the most likely fixed positions for the target using the bearing lines that were two minutes old or less. Subjects verbally stated the selected fixed positions, and a test monitor circled these positions on an ASW tactical display score sheet and recorded subjects' time to analyze the format. Operator accuracy in interpreting data from the displays and time to analyze the fixed positions were statistically improved with the use of color.
Air traffic controllers almost always work from memory of inputs from various sources and from operations performed on the displayed data. On rare occasions air traffic control displays are not operative for periods ranging from seconds to minutes. On these occasions a flight data strip hard copy that lifts current data for departing, arriving and enroute aircraft can be referenced. Because air traffic controllers do not have time to obtain all the information from a flight data strip on each aircraft, the air traffic controllers must rely upon their memory when their displays are not functioning. By necessity air traffic controllers must have a certain minimum performance level for short term and working memory in an air traffic control (ATC) task specific situation. However, at the present time there is no task specific selection criteria for screening ATC candidates which would be useful in reducing ATC candidate attrition rates. Furthermore, there is no present method for quantitatively measuring air traffic controller job performance against either a comparative or standard performance criteria. Therefore, a need exists for a quantitative method for measuring the performance of ATC candidates and air traffic controllers in an ATC task specific environment. The use of color encoded displays may be used to solve this problem.